This invention relates to the treatment of tissues, in particular blood vessels, with therapeutic liquids, such as solutions of genes encoding therapeutic products.
A number of surgical procedures, and in particular minimally invasive surgical procedures, involve ex vivo treatment of blood vessels and other tissues prior to introduction of the tissues into patients. An example of this is the treatment of vein or arterial grafts to be used in cardiac bypass procedures; such grafts can be rendered less susceptible to stenosis by ex vivo treatment of the grafts, prior to their introduction into patients, with therapeutic solutions, e.g., those containing genes encoding stenosis-inhibiting products (i.e., RNAs or proteins). Preferably, such treatment is carried out under pressure, as is described in U.S. Pat. Nos. 5,766,901 and 5,922,687, which are hereby incorporated by reference.
The invention provides a method and an apparatus for exposing a tissue to a treatment medium in a controlled fashion, so that treatment is conducted in an effective, efficient, and safe manner.
Accordingly, the invention features a method for treating a biological tissue (e.g., an elongate biological tissue, such as a blood vessel (e.g., a vein or an artery)) with a therapeutic liquid solution by (a) placing the tissue in an inner trough-shaped chamber; (b) inserting the resultant trough-held tissue into a closable outer chamber; (c) closing the outer chamber; and (d), before or after step (c), infusing the solution into the outer chamber (e.g., by use of a syringe) so that it contacts the tissue.
Optionally, before step (c), the inner trough-shaped chamber is removed from the outer chamber; the outer chamber is closed by means of a removable cap; or the therapeutic liquid solution in the outer chamber contacts the tissue under pressure.
The outer chamber can include or consist of an elongate tubular structure, which consists of, for example, two or more tubular segments that are reversibly hinged to one another, e.g., so as to allow flexion between the segments. The outer chamber containing the tissue and the treatment medium can be fashioned from modular components and/or be tailored to conform to the shape and/or size of the tissue, to minimize the volume requirement of the treatment medium, which can be costly, in particular where it contains DNA or other therapeutic molecules. The walls of the outer chamber can be rigid or flexible; if flexible, such flexibility can, in part, provide a means for adjusting the size and shape of the outer chamber to accommodate the tissue. The outer chamber can also be composed of a collapsible or expandable material that is extended around the tissue to achieve a conformity of size and/or shape.
Before or after step (a), one end of an elongate tissue treated according to the invention can be secured to a canula, e.g., by ligature. The canula can be removably attached to the inner trough-shaped chamber via a gripping mechanism. Also, when placed in the outer chamber with the tissue, the canula can be removably attached to one end of the outer chamber. The therapeutic liquid solution can be introduced into the outer chamber via such a canula.
To facilitate handling and manipulation of the tissue with minimal trauma or injury, the interior surface of the outer chamber and/or the surface of the inner chamber onto which the tissue is placed (herein also referred to as the introducer or trough) can be composed of a biocompatible, slippery material, having a low coefficient of friction.
The invention also includes an apparatus for treating a biological tissue with a therapeutic liquid solution, which consists of (a) a sterile outer chamber that can be closed to be fluid-tight, and that is adapted for enclosing the tissue so that it can be contacted with the solution; and (b) a sterile open inner trough-shaped chamber adapted to be inserted into the outer chamber, and further being adapted to hold the tissue for introduction of the tissue into the outer chamber.
The apparatus can also include a canula that is removably attached to the inner chamber via a gripping mechanism and that is adapted such that one end of an elongate tubular tissue can be removably attached to the canula. When placed in the outer chamber with the tissue and the inner chamber, the canula can be removably attached to one end of the outer chamber, and a cap can be used to seal the end of the outer chamber to which the canula is not attached.
Also, the outer chamber can include or consist of an elongate tubular enclosure, consisting of, for example, two or more segments that are reversibly hinged to one another, e.g., so as to allow flexion between the segments. As is noted above, the outer chamber containing the tissue and the treatment medium can be fashioned from modular components and/or be tailored to conform to the shape and/or size of the tissue, to minimize the volume requirement of the treatment medium, which can be costly, in particular where it contains DNA or other therapeutic molecules. The walls of the outer chamber can be rigid or flexible; if flexible, such flexibility can, in part, provide a means for adjusting the size and shape of the outer chamber to accommodate the tissue. The outer chamber can also be composed of a collapsible or expandable material that is extended around the tissue to achieve a conformity of size and/or shape.
The apparatus can also include a means for altering the pressure in the outer chamber; a syringe for introducing the therapeutic liquid solution into the outer chamber or for altering the pressure in the outer chamber; a device for monitoring the pressure within the outer chamber; a mechanism for automated pressurization of, or delivery of fluid into, the outer chamber; or a feedback mechanism for regulating the pressure, fluid volume, temperature, or oxygen content of the outer chamber.
As is noted above, to facilitate handling and manipulation of the tissue with minimal trauma or injury, the interior surface of the outer chamber and/or the surface of the inner chamber onto which the tissue is placed can be composed of a biocompatible, slippery material, having a low coefficient of friction. Finally, the walls of the outer chamber can be clear, so that the treatment of the biological tissue can be monitored visually.
Other features and advantages of the invention will be apparent from the following detailed description, drawings, and claims.